getting steel flatbed deck flat again

[Sonora Iron]

Use an O/A torch.
How much is the deck bowed? What thickness is it?

[barebackjake]

the worst part maybe 1/4" bow, 1/8" decking

[Cram]

I have hear you can heat shrink bowed areas by applying heat to a bowed area with an OxyAct torch follwed by a cool wet towel. Don't know the exact technique though.

[Sonora Iron]

With only a quarter inch bow in 1/8 inch material the first example may be to aggressive.
You may want to use a series of small circles.
Do not work from the top, inside the concave part of the bow you will make things worse! You have to work on the convex side of the bow, from under the truck. Heat a small circle spray with water and let cool to the touch. First try heating to a dull red. In that thin of material if you heat to cherry red you will cause dimples in the deck. I suggest you do not work too much in one section. Heat 3 or 4 circles in one section then move to another area. Not knowing where or how far apart the ribs are is a challenge to give advice.

[gda]

I just finished reading Sink or Swim Metalworking by Tom Lipton. He has a good section on flame straightening and heat shrinking - describing why it is working - so you know how to make it work. Pages 233-244. You can go to amazon and do a "search inside this book" for "shrink" and preview/read these pages. I'm not going to tell you if you should buy the book or not, that will be your own decision.

[84ZMike]

If it's only 1/4" bowed then weld on the new supports..... use a bottle jack to push it into place..... and 1/4" isn't much of a bow

[J hall]

I agree with Mike. 1/4 is no big deal to get out. Cut your new supports and push them up into place, weld them in and you are done.

[Sonora Iron]

If the metal is stretched, what will he do with the excess?
It will have to go somewhere. I’d tighten those molecules up until they’re shoulder to shoulder.
Other wise the bed may look like a washboard.

[J hall]

If the metal is stretched, what will he do with the excess?
Other wise the bed may look like a washboard.

While it is true that we don't know how far apart the stringers are on his bed, How much stretch could there realistically be with only 1/4" bow?
It will probably never be perfectly flat, but it can be acceptable without a lot of work and expense.

[Sonora Iron]

I think forcing the deck up and installing more ribs is a great idea!
Even if there were a little washboard look to the deck, before stitch welding the deck to the new ribs that is when I would throw a little heat to the high spots from the top, why work under the truck anymore than you have to when you can tighten the deck up from above.